Rudder Position

Muzza
It is foressen in fact to have a flare nose like the one of a war ship but as a "removable " appendage , a sort of Clown red nose but with a nice sliding shape made with balsa or foam to be used only when the risk of “Nose Diving” is present. Personally I do not like the Crazy shape .(by the way the Crazy was developped some 11 years ago if I’m not wrong…)
Claudio

For those who like a flared bow, here is my last design drawings for the Stylet-o’5 .
After all, the deck don’t look very ridiculos and it may deserve a try. The flare is very nice option since do not consume energy when not needed.
Notice is only 140mm wide at LWL and the hull only displace 4294 cm3, the main is only 67.7 cm², further it allow to change bulb size from 2750g up to 3600g.
The deck lines of the bottom drawing are somewhat differents from the ones on the top that is the original before adapting a flare. See differents sections view .

Claudio

I don’t “like” a flared bow, but think it is a practical way to deal with fine forward sections and nosediving.

For me, it seems that in the development classes, it has always got to be function over form. If it works and is fast, do it, and forget about good looks.

When I want a good looking boat, I’ll build something else, like a scale project, a vintage M or a J boat, or maybe an EC12.

Angus - my comments were with regard to Claudio’s Marblehead project - not the Footy. :slight_smile:

Sorry Muzza. I appreciated that. What I was trying to say was that although Claudio’s and my design logic was inmany ways very similar, there are also substantial points of divergence.

A.

Not a silly idea, Claudio! Just different, and not much used. Maybe you can think up something new to make it work well?

Tomohawk,
actually after days or months of thinking I will probably chose a flared bow probably as an “add-on” foam device covered with carbon sheet, to be used with strong winds as well a rudder equipped with ailerons/winglets as already mentioned in this forum. For this late, I will use a third servo since, after considerations, the automatic method will intervene “all the time”, the swing is turning even when the wind is low and therefore the negative incidence of the ailerons/winglets in this case, will produce unnecessary drag .
Claudio

Hello every body,
I got the answer from Mr Grubisa the ISAF -TC Chairman and is confirming that moving winglets on the rudder are forbidden in Class M.
Fixed winglets are instead permitted.
Reading the 10R Rules, according to my understanding, no restrictions are reported on the subject .
Claudio

Does he mean moveable (i.e. under control) or moving (i.e. self operating) or both ?

The reason I ask is that I once had the notion of and end-plate for a rudder that was free within limits to pivot about a horizontal transverse axis. The idea was to allow limited aito-alignment with the direction of flow so as to reduce the end-plate itself causing considerable tip losses on pitching.

Just a thought.

Angus

Angus,
I’m not sure to have understood your remark, anyhow, my idea turns around the use of an horizontal aileron attached to a common rudder that will “move” under command providing a negative incidence of a couple of degr?es . For better understanding, see my drawings on the “Technological discussion”, under Rudder & Winglets. This device should help to avoid noise diving. The command should be activated only when really necessary, as per strong winds during Running. It should furthermore calculated the needed surface taking into account the incidence angle required and the drag produced with and without tilt.
Claudio

Claudio -

if it is any help, I managed to find that the multihull guys (Mini40’s) were setting their fixed winglets on the rudder at a negative 3 degrees. They felt this gave them the least drag in light winds, but offered a fairly quick “down-pressure” for when the winds picked up. As the winds increased, in theory, the winglets created even more down force. Somewhere there must be a point when the wings “down pressure” can’t match wind strength, and the resulting capsize takes place. Not sure where that might take place.

tanks Dick,
as a matter of facts I designed the winglet to move between 0° and -3° - because of the dimensions, this imply a linear movement at the pulling point from 0 to 1.7 mm. - This is why I’m looking to Memory Wires instead of servo or automatic mast system.
What is needed is just a kevlar string inside the rudder linked to an external out of water “memory wire” sitting in the hull + a miniature servo driving a small switch and a small battery.

Actually the rudder is under construction, here the image of the balsa/carbon assy + the tubing and self made spring inside the short tube.

Claudio

Angus, sorry to but in but ive just read your post on wista - were you sailing on wista herself or another tiger, i think aroemarine built five or more of these boats, mick the miller i think another one, im very interested in the history of these boats especialy wista and capt illingworth and what became of them,
i have a woodern jog boat called bourisheen built in 1961 on which im learning to sail, sadly the jog commitee does not have any record of these boats

cheers all

There were three completed on the Mersey from Aeromarine hulls by a variety of doctors - Cliodhna (Drs. Richardson [my father] and Campbell) - Waikari (Dr. Stead) - Martell [Dr. Hargreaves]. Martell was campaigned much less seriously than the other two, which carried off a lot of pots. They were extremely fast to windward: I remember a fairly modern Laurent Giles designed boat of about 35 feet called Motahari taking it out of me to windward - but not by much!

I saw one of them (not sure which) in Inverkip Marina (Clyde) about 10 years ago!

:zbeer: